2-way Sync dosen't pick sub folders

[dmorigin]

⚠️ Before posting ⚠️

• This is a bug, not a question or an enhancement.
• I've searched for similar issues and didn't find a duplicate.
• I've written a clear and descriptive title for this issue, not just "Bug" or "Crash".
• I agree to follow Nextcloud's Code of Conduct.

Steps to reproduce

Delete all Caches/Data for Nextcloud Android App
Deinstall Nextcloud Android App
Reinstall from Google Play Store
Connect App over App Passwrod on Self Hosted Nextcloud Server
[Inside App] Activate 2-way Sync over Menu -> Settings -> Internal 2-way Sync
[Inside App] On File Overview: Selected one Folder (With Sub Folders) -> Open Details -> Select Syncronisation
[Inside App] On File Overview: Mark Same Folder and start first syncronisation bei opening the 3-Points Menu and pressing "Synchronisieren" (using de version)

Expected behaviour

The hole folder including all of the sub folders and files has to be synchronized. There are only mp3 and m3u files in there. The main folder has a total size of 2.7GB.

Actual behaviour

Only the *.m3u files are synchronized, directly under the main folder. But none of the underlying folder, which containing all of the *.mp3 files.

Android version

16 ( Build: BP2A.250605.031.A5 )

Device brand and model

Google Pixel 6

Stock or custom OS?

Stock

Nextcloud android app version

3.32.3

Nextcloud server version

31.0.7

Using a reverse proxy?

No

Android logs

No response

Server error logs

[remote-ip] - [myuser] [05/Sep/2025:15:05:48 +0200] "PROPFIND /remote.php/dav/files/[myuser]/Music/ HTTP/1.1" 207 1326 "-" "Mozilla/5.0 (Android) Nextcloud-android/3.32.3"
[remote-ip] - [myuser] [05/Sep/2025:15:05:48 +0200] "PROPFIND /remote.php/dav/files/[myuser]/Music/Crosing.m3u HTTP/1.1" 207 1408 "-" "Mozilla/5.0 (Android) Nextcloud-android/3.32.3"
[remote-ip] - [myuser] [05/Sep/2025:15:05:48 +0200] "PROPFIND /remote.php/dav/files/[myuser]/Music/Dreaming.m3u HTTP/1.1" 207 1400 "-" "Mozilla/5.0 (Android) Nextcloud-android/3.32.3"
[remote-ip] - [myuser] [05/Sep/2025:15:05:48 +0200] "PROPFIND /remote.php/dav/files/[myuser]/Music/Rausch.m3u HTTP/1.1" 207 1407 "-" "Mozilla/5.0 (Android) Nextcloud-android/3.32.3"
[remote-ip] - [myuser] [05/Sep/2025:15:05:48 +0200] "PROPFIND /remote.php/dav/files/[myuser]/Music/Schleichfahrt.m3u HTTP/1.1" 207 1421 "-" "Mozilla/5.0 (Android) Nextcloud-android/3.32.3"
[remote-ip] - [myuser] [05/Sep/2025:15:05:48 +0200] "PROPFIND /remote.php/dav/files/[myuser]/Music/ HTTP/1.1" 207 13028 "-" "Mozilla/5.0 (Android) Nextcloud-android/3.32.3"

Additional information

No response